1. Field of the Invention
The present invention relates to a semiconductor switch, and more particularly to a semiconductor switch having a disconnectible thyristor, in which a first switching transistor whose switching path is connected into the lead of the thyristor is provided, and having a turn-off current path which connects a control electrode of the thyristor to a terminal of a lead at that side of the first switching transistor which faces away from the thyristor, and to a method for operating the same.
2. Description of the Prior Art
A semiconductor switch of the type generally set forth above is known from the Philips Technical Publication 029, "Electronic Components and Applications", Vol. 3, No. 4, August 1981, pp. 232-237, particularly with reference to FIG. 2. The switching transistor is connected in the cathode lead of the thyristor and is designed as a metal-oxide-semiconductor field effect transistor (MOS-FET) over whose gate the semiconductor switch is controlled. A capacitor is connected in the turn-off current path. The capacitor is charged with a voltage which prepares the thyristor, conditioned in its inhibited condition, for ignition. When the previously-inhibited switching transistor is placed in its conductive condition, an ignition circuit containing a capacitor closes and the thyristor is triggered. Given disconnection of the control voltage from the gate of the switching transistor, the same is blocked, whereupon the load current of the thyristor is entirely conducted into the turn-off current path, namely, until the capacitor and a further capacitor connected in parallel over a diode are charged to the voltage. The thyristor is thereby quenched.